The field of the invention is indwelling nerve block catheters.
Nerve blocks with or without the continuous method can provide total anesthesia and analgesia, prevent and treat postoperative pain in selective patients and surgical procedures. Recent progress in battlefield medicine also demonstrated its feasibility and efficacy in treating trauma pain and promoting rehabilitation in wounded soldiers. Evidence has consistently shown that, when used correctly, it is superior to narcotic based pain management. However, its clinical use is hindered by technique difficulties in nerve finding and complexity of catheter insertions. Currently, there are three ways of locating nerve for performing regional nerve block: 1. Anatomy-based; 2. Motor-evoked potential based; and 3. Ultrasound based. Each technique has its own limitations and difficulties, but all require significant amount of training, extra personal helps and long learning curves. Furthermore, they are time-consuming with widely spread of failed rate ranging from lower 10% up to 20%. Theoretically, single shot and continuous regional nerve block should always work provided it is in the right location with right dose of medication. In practice, however, nerve blocks fail frequently even in the hands of experienced anesthesiologists. We herein provide a nerve finding system that can help experienced as well as novice operator navigate the needle toward targeted nerve in real time, which is simple to use, accurate and less trauma to the patient.
Continuous nerve block (CNB) is essentially the extension of a single short nerve block plus a continuous drug delivery system that can be indwelled inside body for day's even weeks. Current continuous nerve block systems are very complicated involving multiple steps in catheter insertion, securing and connection after initial nerve identification. They provide additional sources of failed or inadequate continuous nerve block even if the initial nerve block is successful. Furthermore, current delivery systems and methods are based on the assumption that inserted catheter, usually 3-5 cm passing the introducer-needle tip, will stay in the proximity of desired nerve and deliver right amount of drugs. This assumption is far from the reality as the introducer-needle tip is the location of the targeted nerve, but not the final location of the inserted catheter tip. Clinical studies have repeatedly shown that it is impossible to accurately control the tip of a flexible catheter once it passes through the needle tip, and therefore there is no guarantee that catheter tip and ultimately delivered drug will be close to the nerve. Additionally, since the diameter of the introducer-needle is significantly larger than the catheter, it can cause back flow of infused medication to the skin surface, reduce the medication volume at the intended nerve location and provide a source of catheter site contamination and infection.
Here we provide a delivery system that combines the introducer-needle with the catheter into one integrated system that functions as an introducer at the nerve finding stage, and as a delivery conduit for continuous nerve block thereafter. It assures the clinician that nerve location is the location of continuous drug delivery point. Additionally, its unique intra-tissue anchor mechanism makes not only securing and removal of catheter easy and less traumatic, but also reduces or prevents backflow of the delivering medication. The delivery system can be a stand-alone equipment or integrated part of our innovative nerve finding system.
Gibbons (U.S. Pat. No. 3,938,529) describes a directionally constrained indwelling ereteral catheter; Eichmann (US2008/0132926) describes an apparatus for accessing the epidural space and having a distal cutting sheath; Interred Medical (Plymouth Minn.) markets a subcutaneous catheter securement system, SecurAcath Universal.